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Canning 101: Why You Shouldn’t Can Like Your Grandmother Did

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When I first started canning in earnest, every few months, I’d wrap up a collection of full jars and ship them off to my parents. I just couldn’t resist sharing all the delicious things I was making with them. One evening, my dad took a moment to call and thank me for the orange marmalade I had recently sent his way. During that phone call, he also made a request. Could I possibly make grape jelly sealed with paraffin wax, like his Grandma Bartlett used to make?

I adore my dad and am nearly always willing to go pretty darn far out of my way to do something to make him happy. Sadly, this was one request that I had to turn down. The reason? It’s just not safe to do it the way Grandma Bartlett used to do it.

Some of the vintage techniques you should avoid include:

Open Kettle Canning: This is the sealing method in which you pour hot jam, jelly or other preserves into a hot jar, quickly wipe the rim and apply the lids and rings. Then you simply allow the heat of the product to produce a seal. While this will typically produce a seal, you don’t have the back-up of the boiling water process, which means that you run a higher risk developing mold or other bacteria in your preserves.

Paraffin Wax Seals: The method my father remembers so fondly. In this technique, you pour thin layers of wax over your jam, until you built up about 1/2 an inch of wax on top of your product. The primary issue with this method is that there’s no way to check your seal. Additionally, these seals have a high rate of failure. My mother remembers her aunt frequently opening jellies sealed in this manner, only to discover that they were furry with mold under the wax.

Upside Down Sealing: This is sealing method found most often in Europe and is a variation on the Open Kettle approach. In it, you fill your jars, wipe rims, apply lids and rings and then, instead of processing you invert the jars and cover with a kitchen towel until they’re cool. While this technique will give you a concave lid and a fairly firm lid, it does not always produce a quality seal (and again, you lack the safety insurance that the boiling water process grants you). Additionally, if you do this with a firm setting jam or jelly, you’ll end up setting your jam up against your lid and not down at the bottom of the jar where it should be.

Steam Canners: A steam canner is a piece of equipment that looks like a cake carrier. It has a very shallow base with a high domed lid. You place it on the stove, pour a small amount of water into the shallow pan, put your jars on top and then cover with the domed lid. The steam then circulates to heat the jars. However, while steam can be hotter than boiling water, it can also exist at much lower temperatures as well. Additionally, it doesn’t have the same heat penetrating abilities as boiling water, so the heat of the processing pot will not penetrate to the core of your jars.

The way I look at canning is this. We all invest our time, money and equipment into our canned goods. It just makes good sense to use the most reliable processing techniques available, to ensure the best outcome possible. As far as I know, the most reliable process (for high acid foods) is a boiling water bath for the length of time prescribed by your recipe.

I think even Grandma Bartlett would change her ways if she was canning in the 21st century.

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